Hand-portable and relay-operated watertight lighting fixtures (battle lanterns) have been used aboard U.S. Navy ships for decades. These lanterns provide numerous functions including passageway and compartment egress lighting in the event of loss of normal lighting, illumination of safes, secure items and important dials, gauges and controls in the event of loss of normal lighting, inter-compartment navigation in the presence of smoke, spray or flooding, and various other portable lighting tasks. The duties of the battle lantern necessitate a level of functionality not required of a standard civilian flashlight. Required characteristics include extreme ruggedness, submersibility and shock-resistance.
Existing battle lanterns typically have a water-tight compartment in which a power supply is housed. The power supply generally comprises one or more rechargeable or non-rechargeable batteries, which are electrically connected to an incandescent lamp through a manual switch or automatic relay. The internal compartment is formed by an outer case having a light port on its forward face. A significant aspect of current lanterns is that the light port is filed and sealed by the lens portion of the incandescent lamp in combination with a sealing gasket. An exemplary lamp used in current lanterns is a 2.35-Watt GE or Philips PAR-36 parabolic reflector incandescent bulb with a tempered glass casing for shatter-resistance.